body {
    width: 100%;
    min-width: 320px;
    min-height: 640px;
    margin: 0 auto;
    font-size: 14px;
    font-family: -apple-system, 'Helvetica Neue', sans-serif;
    color: #666;
    line-height: 1.5;
}

ul {
    margin: 0;
    height: 0;
    list-style: none;
}

.app {
    height: 45px;
}

.app ul li {
    float: left;
    height: 45px;
    background-color: #333;
}

.app ul li:nth-child(1) {
    width: 8%;
}

.app ul li:nth-child(2) {
    width: 10%;
}

.app ul li:nth-child(3) {
    width: 57%;
}

.app ul li:nth-child(4) {
    width: 25%;
}